No Doubles Defense
Late in close games, corners guard the lines and outfielders play deep.
How it actually works. The outfielders move back far enough that nothing gets over them, and the first and third basemen move to within a step or two of the foul lines. Balls that would have been caught in front now fall in, and balls that would have been fielded in the hole now get through. Both are accepted on purpose.
Why it is done, and when it is wrong. This is the clearest expression of a principle that runs through all late-inning defense: with a lead, outs matter less than bases. A single with two outs and nobody on is close to harmless. A double is the tying run in scoring position with one swing. When you are ahead by fewer runs than there are innings left, trading singles for doubles is straightforwardly good, and the fact that it looks passive is not an argument against it.
What people get wrong about it. It is the right call for exactly the situation it was designed for and a bad one everywhere else. A defense that guards the lines in the fourth inning is giving up hits for nothing. And the extra ground it concedes in the gaps is real: the deepest alignment turns some catchable balls into the doubles it was meant to prevent.
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